Image Pickup Lens

ABSTRACT

Embodiments relate to an image pickup lens including a first lens having both convex surfaces, a second lens in the form of a positive meniscus lens and a third lens in the form of a negative meniscus lens, the first lens to the third lens being arranged in sequence from an object side to an image side. The first lens to the third lens are formed of the same material.

CROSS-REFERENCES TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/341,299, filed Jul. 25, 2014, which claims the benefit under 35U.S.C. §119 of Korean Patent Application No. 10-2013-0087781, filed Jul.25, 2013, which are herein incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

Embodiments relate to an image pickup lens and, more particularly, to animage pickup lens, constituent lenses of which have the same index ofrefraction and achieve a compact size and enhanced performance.

2. Related Art

The Recently, conventional film cameras have been replaced with cameramodules for portable terminals using a compact solid-state image pickupdevice (e.g., a Charge Coupled Device (CCD) or a Complementary MetalOxide Semiconductor (CMOS)), Digital Still Cameras (DSCs), camcorders,PC cameras (i.e. image pickup apparatuses attached to personalcomputers) and the like. These image pickup apparatuses are graduallybecoming leaner and smaller.

With this tendency, although a light receiving device, such as a CCD,mounted in a compact image pickup apparatus is being made smaller, animage pickup lens of the image pickup apparatus still occupies thelargest volume of the image pickup apparatus.

Thus, the major issue with regard to a leaner and smaller configurationof the image pickup apparatus is the image pickup lens that forms animage of an object.

Here, problems are not only to merely realize a compact size of theimage pickup lens, but also to achieve high performance of the imagepickup lens corresponding to high performance of the light receivingdevice.

However, the compact image pickup lens is inevitably located close tothe light receiving device, which problematically causes light to beobliquely incident on an image surface of the image pickup apparatus.This results in insufficient light concentration of the image pickuplens as well as extreme variation in the brightness of an image from thecenter to the periphery of the image.

Increasing the number of lenses in consideration of the above-describedproblems, however, inevitably increases the size of the image pickupapparatus and this is also disadvantageous in terms of costs.

Therefore, there is a need to achieve a high performance image pickuplens in consideration of manufacturing cost.

BRIEF SUMMARY

Embodiments provide an image pickup lens having a compact size andenhanced performance.

In one embodiment, an image pickup lens includes a first lens havingboth convex surfaces, a second lens in the form of a positive meniscuslens and a third lens in the form of a negative meniscus lens, the firstlens, the second lens and the third lens being arranged in sequence froman object side to an image side, wherein the first lens to the thirdlens are formed of the same material.

In another embodiment, an image pickup lens includes a first lens in theform of a positive power lens, the first lens having both convexsurfaces, a second lens in the form of a positive power lens and a thirdlens in the form of a negative power lens, the first lens, the secondlens and the third lens being arranged in sequence from an object sideto an image side, wherein the first lens to the third lens have the sameindex of refraction, and wherein power of the second lens is greaterthan power of the first lens and the third lens.

The first lens to the third lens may have the same index of refraction.

At least one of the first lens to the third lens may be a plastic lens.

At least one of the first lens to the third lens may have one or bothaspherical surfaces.

The image pickup lens may further include a stop provided between thefirst lens and the second lens.

The image pickup lens may satisfy the following equation 1:

0.7<f/f1<1.6  <Equation 1>

where, f is a focal distance of the entire optical system and f1 is afocal distance of the first lens.

The image pickup lens may satisfy the following equation 2:

0.8<f/f2<1.5  <Equation 2>

where, f is a focal distance of the entire optical system and f2 is afocal distance of the second lens.

The image pickup lens may satisfy the following equation 3:

−1.6<f/f3<−0.5  <Equation 3>

where, f is a focal distance of the entire optical system and f3 is afocal distance of the third lens.

The image pickup lens may satisfy the following equation 4:

0.5<R1/f<0.7  <Equation 4>

where, R1 is a radius of curvature of an object surface of the firstlens and f is a focal distance of the entire optical system.

The image pickup lens may satisfy the following equation 5:

−0.06<R1/R2<−0.01  <Equation 5>

where, R1 is a radius of curvature of an object surface of the firstlens and R2 is a radius of curvature of an image surface of the firstlens.

The image pickup lens may satisfy the following equation 6:

−0.4<R6/R5<0.2  <Equation 6>

where, R5 is a radius of curvature of an object surface of the thirdlens and R6 is a radius of curvature of an image surface of the thirdlens.

The image pickup lens may satisfy the following equation 7:

0.6<tan θ<0.8<  Equation 7>

where, θ is a half field angle of a maximum image height.

In still another embodiment, a camera module includes an image pickuplens including a first lens in the form of a positive power lens, thefirst lens having both convex surfaces, a second lens in the form of apositive power lens and a third lens in the form of a negative powerlens, the first lens, the second lens and the third lens being arrangedin sequence from an object side to an image side, wherein the first lensto the third lens are formed of the same material, and wherein power ofthe second lens is greater than power of the first lens and the thirdlens, a filter configured to selectively transmit light having passedthrough the image pickup lens based on a wavelength of the light and alight receiving device configured to receive light having passed throughthe filter.

BRIEF DESCRIPTION OF THE DRAWINGS

Arrangements and embodiments may be described in detail with referenceto the following drawings in which like reference numerals refer to likeelements and wherein:

FIG. 1 is a view showing a configuration of an image pickup lens moduleaccording to a first embodiment;

FIG. 2 is a view showing a configuration of an image pickup lens moduleaccording to a second embodiment;

FIG. 3 is a view showing a configuration of an image pickup lens moduleaccording to a third embodiment;

FIG. 4 is a view showing a configuration of an image pickup lens moduleaccording to a fourth embodiment;

FIG. 5 is a view showing a configuration of an image pickup lens moduleaccording to a fifth embodiment;

FIG. 6 is a graph showing aberrations according to the first embodimentshown in FIG. 1;

FIG. 7 is a graph showing aberrations according to the second embodimentshown in FIG. 2;

FIG. 8 is a graph showing aberrations according to the third embodimentshown in FIG. 3;

FIG. 9 is a graph showing aberrations according to the fourth embodimentshown in FIG. 4; and

FIG. 10 is a graph showing aberrations according to the fifth embodimentshown in FIG. 5.

DETAILED DESCRIPTION

Hereinafter, embodiments will be clearly revealed via the followingdescription with reference to the annexed drawings.

All terms provided in this specification have the same meanings asgenerally understood by a person having ordinary skill in the art unlessmentioned otherwise. When terms provided in this specification conflictwith generic meaning of the corresponding terms, the terms should beconstrued based on definitions provided in this specification.

It should be understood that the following description of the disclosureare intended to explain embodiments and not intended to limit the scopeof the disclosure and the same reference numerals throughout thespecification designate the same or similar elements.

In the following description of a configuration of each lens, “objectsurface” refers to a surface of the lens facing an object side on thebasis of the optical axis, and “image surface” refers to a surface ofthe lens facing an image side on the basis of the optical axis.

In addition, “positive power of the lens” refers to a converging lensthat converges parallel beams and “negative power of the lens” refers toa diverging lens that diverges parallel beams.

With regard to features of the disclosure, hereinafter, five types oflenses will be described respectively with reference to FIGS. 1 to 5 andthen embodiments regarding the respective types of lenses will bedescribed in detail with reference to FIGS. 6 to 10.

FIG. 1 is a view showing a configuration of an image pickup lens moduleaccording to a first embodiment.

Referring to FIG. 1, the image pickup lens according to the firstembodiment includes a first lens 10, a second lens 20 and a third lens30 arranged in sequence from an object side to an image side. stop maybe provided between the first lens 10 and the second lens 20, and afilter 40 and a light receiving device 50 may be arranged in sequence.As such, an image pickup lens to be included in a camera module may beconstructed.

The light receiving device 50 may be an image sensor, and a horizontallength and/or a vertical length of a unit pixel of the image sensor maybe 2 μm or less. The above-described embodiment and the followingembodiments may provide an image pickup lens that may be applied to acamera module having a lot of pixels and/or a high resolution. Theaforementioned camera module may include an image sensor or lightreceiving device having a lot of pixels and/or a high resolution and, inthis case, a horizontal length and/or a vertical length of a unit pixelmay be 2 μm or less.

In FIG. 1, “S1” is an object surface of the first lens 10, “S2” is animage surface of the first lens 10, “S3” is an object surface of thesecond lens 20, “S4” is an image surface of the second lens 20, “S5” isan object surface of the third lens 30 and “S6” is an image surface ofthe third lens 30.

These reference characters “Sx” may be equally applied to otherembodiments shown in FIGS. 2 to 5.

The object surfaces of the lenses have shapes as follows. The first lens10 has a convex object surface, the second lens 20 has a concave objectsurface, and the third lens 30 has a convex object surface near theoptical axis.

The image surfaces of the lenses have shapes as follows. The first lens10 has a convex image surface, the second lens 20 has a convex imagesurface, and the third lens 30 has an image surface that is concave nearthe optical axis.

That is, the first lens 10 has convex object and image surfaces, thesecond lens 20 is a positive meniscus lens having a concave objectsurface and a convex image surface, and the third lens 30 is a negativemeniscus lens having a convex object surface and a concave image surfacenear the optical axis.

In addition, the first lens 10 is a positive power lens, the second lens20 is a positive power lens and the third lens 30 is a negative powerlens.

Here, power of the second lens 20 may be greater than power of the firstlens 10 and the third lens 30.

In particular, the third lens 30 has the concave image surface near theoptical axis and the periphery of the concave image surface is convexed,which is advantageous in terms of curvature of field and telecentricity.Moreover, this shape allows a beam to be introduced into the lens at anangle close to a right angle within a range from the center to theperiphery of the image surface (near the optical axis).

At least one of the first lens 10, the second lens 20 and the third lens30 as described above may have one or both aspherical surfaces. This isbecause providing any one of the first lens 10, the second lens 20 andthe third lens 30 with at least one aspherical surface may achieveexcellent effects with regard to correction of various aberrations, moreparticularly, spherical aberration, coma aberration and distortion.

In addition, the first lens 10, the second lens 20 and the third lens 30may be formed of the same material to assure easy power distribution ofthe respective lenses.

In particular, at least one of the first lens 10, the second lens 20 andthe third lens 30 may be a plastic lens fabricated by injection molding.

A glass lens requires a high press temperature for lens formationbecause of a relatively high transition point thereof and, therefore, amold therefor may be easily deformed. In addition, increased moldreplacement times problematically increases fabrication cost of theglass lens. On the other hand, the plastic lens fabricated by injectionmolding has none of the problems associated with fabrication of theglass lens and is advantageous in terms of easy formation of anaspherical lens surface and fabrication of a compact lens.

Note that a surface of the lens provided herein is coated foranti-reflection or enhanced surface hardness.

Meanwhile, an arrangement in which the first lens 10, the second lens 20and the third lens 30 have positive, positive and negative power inorder is an optimal power arrangement that is set in consideration ofoptical performance and manufacturing cost of the image pickup lens andrealization of a compact image pickup apparatus.

The first lens 10 may satisfy the following equation 1.

0.7<f/f1<1.6  <Equation 1>

where, f is a focal distance of the entire optical system and f1 is afocal distance of the first lens 10.

The above equation 1 defines a condition range to impede performancedeterioration, mainly caused by fabrication errors, with regard to thefirst lens 10 having relatively weak power.

More specifically, when exceeding the above range, the power of thefirst lens 10 becomes strong, thus increasing various aberrations causedby the first lens 10 and causing an increased aberration correctionburden of the second lens 20 and the third lens 30.

The second lens 20 may satisfy the following equation 2.

0.8<f/f2<1.5  <Equation 2>

where, f is a focal distance of the entire optical system and f2 is afocal distance of the second lens 20.

The above equation 2 defines a condition range to impede performancedeterioration, mainly caused by fabrication errors, with regard to thesecond lens 20 having relatively strong power.

More specifically, when exceeding the above range, power balance betweenthe respective lenses is broken and it is difficult to achieve a compactand high performance image pickup lens.

The third lens 30 may satisfy the following equation 3.

−1.6<f/f3<−0.5  <Equation 3>

where, f is a focal distance of the entire optical system and f3 is afocal distance of the third lens 30.

The above equation 3 defines a condition range to impede performancedeterioration mainly caused by a coma aberration.

More specifically, when exceeding the above range, power balance betweenthe respective lenses is broken and it is difficult to achieve a compactand high performance image pickup lens.

It is desirable that the equation 1 to the equation 3 be simultaneouslysatisfied.

Meanwhile, the lenses provided herein may satisfy the followingequations with regard to a radius of curvature.

0.5<R1/f<0.7  <Equation 4>

−0.06<R1/R2<−0.01  <Equation 5>

−0.4<R6/R5<0.2  <Equation 6>

where, R1 is a radius of curvature of the object surface S1 of the firstlens 10, R2 is a radius of curvature of the image surface S2 of thefirst lens 10, R5 is a radius of curvature of the object surface S5 ofthe third lens 30, R6 is a radius of curvature of the image surface S6of the third lens 30, and f is a focal distance of the entire opticalsystem.

By satisfying the respective equations with regard to radii of curvatureof the lenses provided herein, aberration correction is implemented withregard to a field angle of each lens. That is, as an incident angle offlux in an image pickup device is controlled to a constant angle,imbalance in the density of flux at an image surface may be reduced.

In the above equation 4, R1/f is a value above zero and below 1. Whenthis range is satisfied, a shape of the first lens 10 for a compactimage pickup lens and power distribution may be easily achieved.

In the above equation 5, R1/R2 has a value below zero. When this rangeis satisfied, a compact image pickup lens may be achieved. Morespecifically, increasing a curvature of the object surface of the firstlens 10 with decreasing distance to the top may result in an increaseddegree of freedom with regard to a curvature of the remaining lenses inthe image pickup lens having a limited length for compactness.

In the above equation 6, an absolute value of R6/R5 is below 1. Whenthis range is satisfied, a shape of the third lens 30 to allow light tobe introduced to the surface of the third lens 30 in a tangentialdirection may be easily achieved, which may reduce an aberration.

It is desirable that the equation 4 to the equation 6 be simultaneouslysatisfied.

Meanwhile, that the image pickup lens of the disclosure satisfies thefollowing equation 7 is advantageous in terms of balance between thelenses.

0.6<tan θ<0.8  <Equation 7>

where, θ is a half field angle of a maximum image height.

Meanwhile, considering a position of the stop relative to the first lens10 to the third lens 30, the stop may be located above an object toachieve telecentricity. In addition, the stop may be located between theimage surface of the first lens 10 and the object surface of the secondlens 20.

Meanwhile, the filter 40 may be an optical member, for example, a flatplate shaped optical member, such as a cover glass for protection of theimage surface, an infrared filter or the like. The light receivingdevice 50 may be an image sensor disposed on a printed circuit board(not shown).

The image pickup lens according to the first embodiment shown in FIG. 1having the above-described features may have detailed features asrepresented in the following table 1 and table 2.

Here, table 1 represents lens data regarding each lens surface and table2 represents a Koenig constant k and aspherical surface coefficients Ato E of each lens surface. In table 1 and table 2, “*” designates anaspherical surface.

TABLE 1 Radius of Thickness Index of Abbe Curvature or DistanceRefraction Number Sx (R) (d) (N) (vd) 1* 1.0000 0.415 1.53 56.5 2*−20.0000 0.100 Stop Infinity 0.242 1.53 56.5 3* −1.1466 0.610 4* −0.50730.100 1.53 56.5 5* −5.5044 0.354 6* 0.8103 0.142 1.52 54.5 7  Infinity0.400 8  Infinity 0.095 Image Infinity 0.041 sensor

TABLE 2 Sx k A B C D E 1* −0.22058 −0.09741 −0.14192 −0.54464 −5.087143.51683 2* 0.00000 −0.27906 −0.92548 1.00231 0.16230 −0.38292 3* 0.26340−1.20012 0.01391 −30.75299 124.69855 195.34033 4* −1.10998 0.52855−7.19480 32.54181 −82.30582 91.19558 5* 0.00000 −0.88762 −0.094803.48596 −6.10504 2.22288 6* −4.17723 −0.63487 0.85859 −0.78629 0.32075−0.06604

FIG. 6 is a graph showing aberrations according to the first embodiment.In the graph, longitudinal spherical aberration, astigmatism anddistortion are shown from the left in sequence.

In FIG. 6, the Y-axis refers to a size of an image and the X-axis refersto a focal distance (mm) and distortion (%). Curves of FIG. 6 areinterpreted as having a higher aberration correction function withdecreasing distance to the Y-axis.

More specifically, in FIG. 6, a longitudinal spherical aberration iswithin a range of −0.060 mm to +0.025 mm, astigmatism is within a rangeof −0.121 mm to +0.03 mm and distortion is within a range of 0% to+8.1%. The image pickup lens according to the first embodiment exhibitsexcellent numerical values of a longitudinal spherical aberration,astigmatism and distortion because image values are close to the Y-axisin almost all fields.

FIG. 2 is a view showing a configuration of an image pickup lens moduleaccording to a second embodiment.

Referring to FIG. 2, except for slight shape differences, the samefeatures of the respective lenses and the same equations as those of theimage pickup lens according to the first embodiment shown in FIG. 1 areapplied.

The image pickup lens according to the second embodiment shown in FIG. 2having the above-described features may have detailed features asrepresented in the following table 3 and table 4.

Here, table 3 represents lens data regarding each lens surface and table4 represents a Koenig constant k and aspherical surface coefficients Ato E of each lens surface. In table 3 and table 4, “*” designates anaspherical surface.

TABLE 3 Thickness Index Radius of or of Abbe Curvature DistanceRefraction Number Sx (R) (d) (N) (vd) 1* 1.2000 0.451 1.53 56.5 2*−40.0000 0.100 Stop Infinity 0.231 1.53 56.5 3* −1.6512 0.734 4* −0.58310.100 1.53 56.5 5* 4.4787 0.352 6* 0.6832 0.163 1.52 54.5 7  Infinity0.400 8  Infinity 0.157 Image Infinity 0.010 sensor

TABLE 4 Sx k A B C D E 1* 0.23969 −0.06312 −0.10784 0.03389 −3.987944.52810 2* 0.00000 −0.13479 −0.96231 0.70107 1.43487 5.42855 3* −0.29112−0.76014 −2.90901 −22.62070 153.24376 −64.04640 4* −0.81839 0.22735−6.60502 35.16093 −95.72353 98.37479 5* 0.00000 −1.30457 −0.815274.19577 −3.10202 0.00000 6* −2.62278 −0.77957 0.91902 −0079340 0.41116−0.10237

FIG. 7 is a graph showing aberrations according to the secondembodiment. In the graph, a longitudinal spherical aberration,astigmatism and distortion are shown from the left in sequence.

In FIG. 7, the Y-axis refers to a size of an image and the X-axis refersto a focal distance (mm) and distortion (%). Curves of FIG. 7 areinterpreted as having a higher aberration correction function withdecreasing distance to the Y-axis.

More specifically, in FIG. 7, a longitudinal spherical aberration iswithin a range of −0.030 mm to +0.010 mm, astigmatism is within a rangeof −0.011 mm to +0.029 mm and distortion is within a range of 0%/o to+4.6%. The image pickup lens according to the second embodiment exhibitsexcellent numerical values of a longitudinal spherical aberration,astigmatism and distortion because image values are close to the Y-axisin almost all fields.

FIG. 3 is a view showing a configuration of an image pickup lens moduleaccording to a third embodiment.

Referring to FIG. 3, except for slight shape differences, the samefeatures of the respective lenses and the same equations as those of theimage pickup lens according to the first embodiment shown in FIG. 1 areapplied.

The image pickup lens according to the third embodiment shown in FIG. 3having the above-described features may have detailed features asrepresented in the following table 5 and table 6.

Here, table 5 represents lens data regarding each lens surface and table6 represents a Koenig constant k and aspherical surface coefficients Ato E of each lens surface. In table 5 and table 6, “*” designates anaspherical surface.

TABLE 5 Thickness Index Radius of or of Abbe Curvature DistanceRefraction Number Sx (R) (d) (N) (vd) 1* 1.1847 0.593 1.53 56.5 2*−64.0000 0.100 Stop Infinity 0.312 1.53 56.5 3* −1.5126 0.569 4* −0.51150.110 1.53 56.5 5* 305.7291 0.350 6* 0.6475 0.166 1.52 54.5 7  Infinity0.400 8  Infinity 0.054 image Infinity 0.025 sensor

TABLE 6 Sx k A B C D E 1* −0.42727 −0.01345 −0.10213 1.03775 −3.592663.38099 2* .00000 0.04876 −0.60114 1.34124 −31.31626 146.79033 3*−5.38004 −1.05359 −0.13066 −27.11245 112.56587 25.26501 4* −1.004190.50806 −6.80090 31.35831 −87.96181 101.59358 5* .00000 −1.07746 0.132824.05805 −5.89792 2.23623 6* −4.49510 −0.56671 0.74440 −0.67203 0.33786−0.07615

FIG. 8 is a graph showing aberrations according to the third embodiment.In the graph, a longitudinal spherical aberration, astigmatism anddistortion are shown from the left in sequence.

In FIG. 8, the Y-axis refers to a height of an image and the X-axisrefers to a focal distance (mm) and distortion (%). Curves of FIG. 8 areinterpreted as having a higher aberration correction function withdecreasing distance to the Y-axis.

More specifically, in FIG. 8, a longitudinal spherical aberration iswithin a range of −0.046 mm to +0.017 mm, astigmatism is within a rangeof −0.031 mm to +0.032 mm and distortion is within a range of 0% to+10.0%. The image pickup lens according to the third embodiment exhibitsexcellent numerical values of a longitudinal spherical aberration,astigmatism and distortion because image values are close to the Y-axisin almost all fields.

FIG. 4 is a view showing a configuration of an image pickup lens moduleaccording to a fourth embodiment.

Referring to FIG. 4, except for slight shape differences, the samefeatures of the respective lenses and the same equations as those of theimage pickup lens according to the first embodiment shown in FIG. 1 areapplied.

The image pickup lens according to the fourth embodiment shown in FIG. 4having the above-described features may have detailed features asrepresented in the following table 7 and table 8.

Here, table 7 represents lens data regarding each lens surface and table8 represents a Koenig constant k and aspherical surface coefficients Ato E of each lens surface. In table 7 and table 8, “*” designates anaspherical surface.

TABLE 7 Thickness Index Radius of or of Abbe Curvature DistanceRefraction Number Sx (R) (d) (N) (vd) 1* 1.0847 0.513 1.53 56.5 2*−75.0000 0.100 Stop Infinity 0.256 1.53 56.5 3* −2.1234 0.609 4* −0.56080.110 1.53 56.5 5* −2.6529 0.350 6* 0.8138 0.129 1.52 54.5 7  Infinity0.400 8  Infinity 0.072 Image Infinity 0.028 sensor

TABLE 8 Sx k A B C D E 1* −0.39903 −0.00184 −0.11289 0.93044 −3.808163.34700 2* 0.00000 0.02180 −0.34103 2.59422 −46.44405 146.79033 3*−12.42691 −0.84968 1.30066 −2.63840 112.21888 25.26501 4* −1.02365.052879 −6.56635 31.98029 −86.65857 104.35214 5* 0.00000 −1.152660.00435 3.99054 −5.87608 2.23940 6* −5.46860 −0.53998 0.73218 −0.670030.33486 −0.08210

FIG. 9 is a graph showing aberrations according to the fourthembodiment. In the graph, a longitudinal spherical aberration,astigmatism and distortion are shown from the left in sequence.

In FIG. 9, the Y-axis refers to a size of an image and the X-axis refersto a focal distance (mm) and distortion (%). Curves of FIG. 9 areinterpreted as having a higher aberration correction function withdecreasing distance to the Y-axis.

More specifically, in FIG. 9, a longitudinal spherical aberration iswithin a range of −0.048 mm to +0.013 mm, astigmatism is within a rangeof −0.082 mm to +0.001 mm and distortion is within a range of 0% to+8.4%. The image pickup lens according to the fourth embodiment exhibitsexcellent numerical values of a longitudinal spherical aberration,astigmatism and distortion because image values are close to the Y-axisin almost all fields.

FIG. 5 is a view showing a configuration of an image pickup lens moduleaccording to a fifth embodiment.

Referring to FIG. 5, except for slight shape differences, the samefeatures of the respective lenses and the same equations as those of theimage pickup lens according to the first embodiment shown in FIG. 1 areapplied.

The image pickup lens according to the fifth embodiment shown in FIG. 5having the above-described features may have detailed features asrepresented in the following table 9 and table 10.

Here, table 9 represents lens data regarding each lens surface and table10 represents a Koenig constant k and aspherical surface coefficients Ato E of each lens surface. In table 9 and table 10, “*” designates anaspherical surface.

TABLE 9 Thickness Index Radius of or of Abbe Curvature DistanceRefraction Number Sx (R) (d) (N) (vd) 1* 1.1374 0.396 1.53 56.5 2*−95.0000 0.100 Stop Infinity 0.188 1.53 56.5 3* −0.9328 0.498 4* −0.59170.187 1.53 56.5 5* −10.5147 0.337 6* 2.977 0.102 1.52 54.5 7  Infinity0.400 8  Infinity 0.426 Image Infinity 0.039 sensor

TABLE 10 Sx k A B C D E 1* −0.54329 0.00855 −0.11736 0.61026 −4.790021.39692 2* 0.00000 −0.05703 −1.48381 6.86563 −36.26306 66.55961 3*0.87830 −0.91923 43.9174 −6.85949 70.56706 25.26045 4* −0.72914 0.35344−5.66468 33.86951 −88.40531 94.9630 5* 0.00000 −0.47299 −0.53539 2.85336−2.77558 −1.87737 6* 3.00517 −0.68935 0.47109 −0.49436 0.30639 −0.20346

FIG. 10 is a graph showing aberrations according to the fifthembodiment. In the graph, a longitudinal spherical aberration,astigmatism and distortion are shown from the left in sequence.

In FIG. 10, the Y-axis refers to a size of an image and the X-axisrefers to a focal distance (mm) and distortion (%). Curves of FIG. 10are interpreted as having a higher aberration correction function withdecreasing distance to the Y-axis.

More specifically, in FIG. 10, a longitudinal spherical aberration iswithin a range of −0.069 mm to +0.025 mm, astigmatism is within a rangeof −0.121 mm to +0.039 mm and distortion is within a range of −2.48% to+0.83%. The image pickup lens according to the fifth embodiment exhibitsexcellent numerical values of a longitudinal spherical aberration,astigmatism and distortion because image values are close to the Y-axisin almost all fields.

A camera module including the above-described image pickup lens may beincorporated in various digital appliances, such as digital cameras,smart phones, laptop computers, tablet PCs and the like.

The above-described technical features may result in a compact highperformance image pickup lens which is optimized in terms of constituentmaterial, shape and power distribution.

As is apparent from the above description, the embodiments may providean image pickup lens having a compact size and enhanced performance.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. An image pickup lens comprising: a first lens, asecond lens and a third lens arranged in sequence from an object side toan image side, wherein the first lens to the third lens are formed ofthe same material, and wherein the image pickup lens satisfies thefollowing equation 2:0.8<f/f2<1.5  <Equation 2> where, f is a focal distance of the entireoptical system and f2 is a focal distance of the second lens.
 2. Theimage pickup lens according to claim 1, wherein the first lens havingboth convex surfaces.
 3. The image pickup lens according to claim 1,wherein the second lens in the form of a positive meniscus lens.
 4. Theimage pickup lens according to claim 1, wherein the third lens in theform of a negative meniscus lens.
 5. The image pickup lens according toclaim 1, wherein the first lens to the third lens have the same index ofrefraction.
 6. The image pickup lens according to claim 1, wherein atleast one of the first lens to the third lens is a plastic lens.
 7. Theimage pickup lens according to claim 1, wherein at least one of thefirst lens to the third lens has one or both aspherical surfaces.
 8. Theimage pickup lens according to claim 1, further comprising an stopprovided between the first lens and the second lens.
 9. The image pickuplens according to claim 1, wherein the image pickup lens satisfies thefollowing equation 1:0.7<f/f1<1.6  <Equation 1> where, f is a focal distance of the entireoptical system and f1 is a focal distance of the first lens.
 10. Theimage pickup lens according to claim 1, wherein the image pickup lenssatisfies the following equation 3:−1.6<f/f3<−0.5  <Equation 3> where, f is a focal distance of the entireoptical system and f3 is a focal distance of the third lens.
 11. Theimage pickup lens according to claim 1, wherein the image pickup lenssatisfies the following equation 4:0.5<R1/f<0.7  <Equation 4> where, R1 is a radius of curvature of anobject surface of the first lens and f is a focal distance of the entireoptical system.
 12. The image pickup lens according to claim 1, whereinthe image pickup lens satisfies the following equation 5:−0.06<R1/R2<−0.01  <Equation 5> where, R1 is a radius of curvature of anobject surface of the first lens and R2 is a radius of curvature of animage surface of the first lens.
 13. The image pickup lens according toclaim 1, wherein the image pickup lens satisfies the following equation6:−0.4<R6/R5<0.2  <Equation 6> where, R5 is a radius of curvature of anobject surface of the third lens and R6 is a radius of curvature of animage surface of the third lens.
 14. The image pickup lens according toclaim 1, wherein the image pickup lens satisfies the following equation7:0.6<tan θ<0.8  <Equation 7> where, θ is a half field angle of a maximumimage height.
 15. An image pickup lens comprising: a first lens, asecond lens and a third lens being arranged in sequence from an objectside to an image side, wherein the first lens to the third lens areformed of the same material, wherein the image pickup lens satisfies thefollowing equation 7:0.6<tan θ<0.8  <Equation 7> where, θ is a half field angle of a maximumimage height.
 16. The image pickup lens according to claim 15, whereinpower of the second lens is greater than power of the first lens and thethird lens.
 17. The image pickup lens according to claim 15, wherein thefirst lens is in the form of a positive power lens, and the first lenshas both convex surfaces.
 18. The image pickup lens according to claim15, wherein the second lens in the form of a positive power lens. 19.The image pickup lens according to claim 15, wherein the third lens inthe form of a negative power lens.
 20. An image pickup lens comprising:a first lens, a second lens and a third lens being arranged in sequencefrom an object side to an image side, wherein the image pickup lenssatisfies the following equation 2 and equation 7:0.8<f/f2<1.5  <Equation 2> where, f is a focal distance of the entireoptical system and f2 is a focal distance of the second lens,0.6<tan θ<0.8  <Equation 7> where, θ is a half field angle of a maximumimage height.
 21. camera module comprising: an image pickup lensincluding a first lens, a second lens and a third lens arranged insequence from an object side to an image side, and wherein the firstlens to the third lens are formed of the same material; a filterconfigured to selectively transmit light, having passed through theimage pickup lens, based on a wavelength of the light; and a lightreceiving device configured to receive light having passed through thefilter, wherein the image pickup lens satisfies the following equation2:0.8<f/f2<1.5  <Equation 2> where, f is a focal distance of the entireoptical system and f2 is a focal distance of the second lens.